Project Summary: We propose to purchase Cytek Aurora flow cytometric analyzer as a major component for Ross Flow Cytometry Core in Johns Hopkins University (JHU) School of Medicine. Aurora from Cytek Biosciences is a full-spectrum flow cytometer based on a new technology with an efficient excitation and a high gain emission system containing APD (Avalanche Photodiode) and CWDM (Coarse Wavelength Division Multiplexing). This innovative architecture can give superior sensitivity and resolution, minimal fluorochrome overspill, and excellent auto-fluorescence subtraction. The proposed instrument combines a 4-laser analyzer system (Blue 488-nm, Red 640-nm, Violet 405-nm, and Yellow-Green 561-nm), and an integrated high throughput sampler (HTS). No such instrument is presently available at JHU. The proposed state-of-the-art flow analyzer is needed to address the needs of 25 research groups on JHU medical campus, who have NIH-funded projects or from other federal funding agents. The projects with several research aims can strongly benefit from the improved technical capabilities provided by this equipment for 1) analyzing multi-color with high sensitivity to detect dim and rare populations, as well as cells and assay with high auto-fluorescence background; 2) detecting unique fluorochromes by Yellow-Green laser; 3) analyzing small particles; and 4) high throughput screening. Ross Flow Cytometry Core is under the administration and management of Department of Medicine and Division of Hematology, and is oversighted by the advisory committee that will continue to provide recommendations for successful installation and management of new Aurora cytometer. For the past 5 years, Ross Flow Cytometry Core has provided services to more than 240 laboratories, not only from JHU, but also from local academic institutes and biotech companies. Ross Flow Cytometry Core currently has two flow analyzers, BD Calibur and BD LSR II, which only provide basic flow cytometric analyses with limited applications, are not upgradable, and lack the capability 1) to effectively have multi-color analysis with superior sensitivity and resolution, minimal spillover, and optimal auto-fluorescence subtraction for dim signals, rare cell populations, and high auto- fluorescence background; 2) to analyze exosomes and other extracellular vesicles (EVs); 3) to read multi-well plates for high-throughput screening; and 4) to analyze cells labeled with certain fluorescent proteins and fluorochromes (such as mCherry and dyes with narrow excitation peak at around 561nm). The proposed instrument should fulfill the gaps between current services and innovative applications for research projects.